Process of making dialkylbarbituric acid.



UNITED STATES'PATENT OFFICE.

MAX ENGELMANN, ELBERFEL U, GERMANY, ASSIGNOR TOFARBENFABRIKEN VORM. FRIEDR. BAYER & 00., OF ELBERFELD, GERMANY, A CORPORATION OF GERMANY.

1:ROCESS OF MAKING DIALKYLBARBITURIC ACID.

sameness.

To all whom it mcy concern:

Beit known that 1, MAX. ENGELMAN doctor of philosophy, chemist, citizen of the GermanKEmpire, residing at Elberfeld, Germany, ing'dom of Prussia, have invented new and useful Improvements in Processes of Making Dialkylbarhituric Acids, of which the following is a specification.

My invention relates to a new process for the manufacture and production of dialkvl' barbituric acids 2 4.6 trioxy 5- dialkylpyrimidines) being, as is known, valuable soporifics. The new process consists in heating the dialkyl malonyl diurethanes, havingthe formula;

a oo-NH-oooR (R meaning alkyl radicles).

Theyielr of dialkyl barbitu-ric acids can be increased by adding to the reaction mass carbonio acid derivativeasuch as urea, diphenvl carbonate, or the like. As far as I could hitherto ascertain, these substances increase the yield without, however, entering into the reaction.

parts being by Weight:

The use of these carbonic acid derlvatives has been specifically described and claimed in my. divisional application, Serial No. 384,079, filed July 16, 1907 By heating the dialkyl malonyl lIIIIB,

th ones by themselves dialkyl harbituric acids and dialkyl carbonates are formedprohably according to the follow ing formula: R COL-M14300}; R 004m t o o CO+OR-COOR.

If the thus obtained melt isextracted with boiling Water the dialkyl bari'iituric acid can be separated from the impurities. However, in order to get the pure dialkyl harbituric acid, it is advantageous to trcatthe melt for further purification V\ ith dilute alkaline solutions. .If dilute ammonia is used then the ammonia'cal liquid is filtered from unchanged diurethane, the filtrate boiled to Specification of Letters Patent. Application filed July 20. 1906. Beria1No.321.084.-

iatented Feb. 18 1908.

I I heated to from 200 to 210 C. for Shows,

and the melt is dissolved in an a ueous ammonia solution. This solution is i1 tered and the filtrate -is freed from ammonia by boiling it. The diethyl barbituric ac id separates while cooling. It can be further urified by recrystallization from water. The process is carried out in an analogous manner or the production of other dialkyl barbituric acids, such as dipropyl barbituric acid, methylethyl barhituric acid, or the like.

Having now described my invention and in what manner the same is to be performed, what I claim as new and desire to secureby Letters Patent, is:

1. The processfor the production of dialkyl barbiturio acids, having the above given general formula, which process consists in first heating dialkyl malonyl drure'thanes and ISO- lating from the thus obtained melt the results ing 5-dialkyl-2.4.6-trioxypyrimidines, stantially as described.

2. The rocess for the roduction of dialkyl bar ituric acids, which rocess consists in first heating dialkyl/ina onyl diuresubvthanes, dissolving the thusobta'ined melt in ammonia, filtering the liquid, boiling the filtrate to drive off the ammonia, and crystallizing the resulting 5dialkyl2.4. 6-trioxypyrimidines therefrom, substantially as described. i

3. The process for the production of diethyl barbituric acid, having the above given general formula, which process consists in first heating diethyl malonyldiurethanes and isolating-from the thus obtained melt the resulting 5-diethyl -2.4.6 trioxypyrimidine, substantially as described.

, 4. The process. for the production of diethyl barbituric acid, which process consistsin first heating diethyl malonyl, d'iure-' thanes, dissolving the thus obtained melt in ammonia, filtering the liquid, boiling the filtrate to drive ofl the ammonia, and crystalliying the resulting 5-diethyl-2.4.6.-trioxypyrimidine therefrom, substantially as described.

In testimony whereof'I have hereunto set my hand in the presence oftwo subscribing witnesses.

MAX ENGELMANN. [1 s.]

Witnesses:

O'r'ro Komo, J. A. krr'rnnsnaos. 

